Involvement of a novel zinc finger protein, MIZF, in transcriptional repression by interacting with a methyl-CpG-binding protein, MBD2
Involvement of a novel zinc finger protein, MIZF, in transcriptional repression by interacting with a methyl-CpG-binding protein, MBD2
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DOI：
10.1074/jbc.m107048200
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发表时间：
2001-11-16
影响因子：
4.8
通讯作者：
Homma, Y
中科院分区：
文献类型：
--
作者：
Sekimata, M;Takahashi, A;Homma, Y
Mbd2是一种甲基CpG结合蛋白，是MeCP1组蛋白去乙酰化酶(HDAC)复合体的组成部分，在DNA甲基化介导的转录抑制中起关键作用。为了了解甲基化相关抑制的分子基础，我们试图通过酵母双杂交系统来鉴定Mbd2相互作用的蛋白。以Mbd2为诱饵，分离出一种新的锌指蛋白MIZF。体外结合实验和免疫沉淀实验证实Mbd2与MIZF之间存在直接相互作用。存在于MIZF的C-末端区域的七个锌指中的四个需要与Mbd2结合。MIZF mRNA在所有被检测的人类组织和细胞系中都有表达。MIZF和Mbd2的亚细胞定位不同，虽然两者共定位于细胞核的某些区域；MIZF广泛分布在核质区，而Mbd2优先定位于主要卫星。报告分析表明，MIZF显著地取消了转录活性。这种抑制作用可被HDAC抑制剂曲古抑素A减弱，并完全依赖于与MBD2的相互作用。这些结果表明，MIZF在细胞中大量存在，并通过与Mbd2结合和募集含有HDAC的复合体而发挥负转录调节作用。
MBD2, a methyl-CpG-binding protein, is a component of the MeCP1 histone deacetylase (HDAC) complex and plays a critical role in DNA methylation-mediated transcriptional repression. To understand the molecular basis of the methylation-associated repression, we attempted to identify MBD2-interacting proteins by a yeast two-hybrid system. Using MBD2 as bait, we isolated a novel zinc finger protein, referred to as MIZF. A direct interaction between MBD2 and MIZF was confirmed by in vitro binding assays and immunoprecipitation experiments. Four of seven zinc fingers present in the C-terminal region of MIZF are required for binding with MBD2. The MIZF mRNA is expressed in all human tissues and cell lines examined. The subcellular localization of MIZF is distinct from that of MBD2, although both proteins co-localize in some areas of the nuclei; MIZF localizes diffusely in the nucleoplasmic region, whereas MBD2 preferentially localizes in major satellites. A reporter assay demonstrated that MIZF significantly abrogates transcriptional activities. This repression is attenuated by an HDAC inhibitor, trichostatin A, and is completely dependent on the interaction with MBD2. These results suggest that MIZF is abundantly present in cells and functions as a negative regulator of transcription by binding to MBD2 and recruiting HDAC-containing complexes.